As a method of improving communication efficiency (a substantial transmission speed in consideration of a total throughput of a system and occurrence of reception errors), there has been proposed a scheme for adaptively selecting communication parameters such as a modulation scheme, a channel coding rate, an error correction coding scheme, a spreading rate, a code multiplexing number and transmission power, based on indices indicating a propagation path state and reception quality, such as received signal power and an SINR (Signal to Interference plus Noise power Ratio) (see the following Non-Patent Document 1). Particularly, a scheme for adaptively selecting modulation parameters such as the modulation scheme and the channel coding rate is referred to as “adaptive modulation scheme”.
Moreover, in a communication system which is composed of a base station apparatus and a plurality of terminal apparatuses, and uses multicarrier communication in communication from the base station apparatus to the terminal apparatus (downlink), there has been considered a scheme for scheduling for assigning a channel to each terminal apparatus, and further, for the downlink, performing adaptive modulation for each channel consisting of one subcarrier or several subcarriers, depending on downlink signal reception quality of each channel in each terminal apparatus (see the following Non-Patent Document 2 and Non-Patent Document 3).
It should be noted that, in the communication system employing the scheduling or the adaptive modulation scheme based on the reception quality of the terminal apparatus, in order to assign the channel or to determine the modulation parameters, a communication partner needs to be notified of the indices indicating the propagation path state and the reception quality, such as the received signal power and the SINR, of the channel used for the communication.
In the communication system as described above, each terminal apparatus needs to notify the base station apparatus of channel quality information representing the reception quality related to each channel, by using a control channel or the like for communication from the terminal apparatus to the base station apparatus (uplink). Consequently, there has been a problem in that an amount of information in the channel quality information transmitted in the unlink enormously increases in proportion to the number of the terminal apparatuses and the number of the channels.
In order to improve the above described problem, for the purpose of reducing the amount of information in the channel quality information transmitted in the uplink, there has been proposed a method in which a predetermined number of channels with good reception quality are selected in order of goodness of the reception quality, from all the channels assigned to each terminal apparatus by a base station for communication, and the base station apparatus is notified of only the reception quality of those some channels (see the following Patent Document 1, Patent Document 2, Non-Patent Document 3 and Non-Patent Document 4).    Patent Document 1: JP Patent Publication (Kokai) No. 2004-208234    Patent Document 2: JP Patent Publication (Kokai) No. 2006-50545    Non-Patent Document 1: Kishiyama et al., “Experimental Evaluations of Adaptive Modulation and Channel Coding in Forward Link for VSF-OFCDM Broadband Wireless Access”, The Technical Report of the Institute of Electronics, Information and Communication Engineers, May 2003, RCS2003-25    Non-Patent Document 2: Maehara et al., “On OFDM/TDD Transmission Scheme with Subcarrier Adaptive Modulation”, 2001 General Conference of the Institute of Electronics, Information and Communication Engineers, March 2001, B-5-100, p. 498    Non-Patent Document 3: “CQI report and scheduling procedure”, 3GPP, TSG-RAN WG1 Meeting #42bis, R1-051045, October 2005    Non-Patent Document 4: “Sensitivity of DL/UL Performance to CQI-Compression with Text Proposal”, 3GPP, TSG-RAN WG1 ad hoc meeting on LTE, R1-060228, January 2006